Read "FILE AND DIRECTORY OWNERSHIP AND PERMISSIONS" in man mount.cifs
good advice - RTFM ! At least your post count went up.
For those you have similar issues you might need to use the uid and gid options
mount -t cifs //192.168.0.10/mydisk/tvshows /media/tvshows -o uid=pi, gid=pi
uid and gid are the user/group that require write access.